Credit

Caption

HK97 bacteriophage procapsid. Molecular model showing the structure of the prohead-I procapsid of the HK97 bacteriophage. Bacteriophages are viruses that infect bacteria, in this case enterobacteria such as Escherichia coli. Prohead-I is a preliminary formation of the phage head capsid, which can be disassembled and reassembled. The capsid is a protein shell that encloses the phage's genetic material. This procapsid has icosahedral symmetry. One of the functions of the capsid is to aid the transmission of the viral genetic material into host cells.